1. Field of the Invention
The present invention relates to a portable device for the preparation of and intravenous delivery of sterilized nutrients or medicinal solutions for use in patients who, for one reason or another, are unable to eat or accept nutrients or medicines by mouth. The device will be used under conditions in which Total Parenteral Nutrition (TPN) is indicated or where the administration of drugs, electrolytes or nutrients cannot be taken by mouth.
2. Brief Description of Prior Arts
The existing method and device by Biegler et al (Aug. 11, 1981, U.S. Pat. No. 4,282,863) invented for the preparation of sterile solutions of nutrients from dry ingredients for intravenous use relies heavily on gravity filtration of the solutions through a 0.22 micron bacteria filter. Their method and device proposes that the nutrient composition (i.e. concentration) of the final solution must be capable of passing through the filter within a 2 hour test period, if not, the nutrient composition of the solution is not preferred by their method and device (re: column 3, lines 8 to 20; column 5, lines 36 to 44). In support of his patent, Beigler et al provide data that hot water (185.degree. F.) solutions containing 25% dextrose or one containing 4.5% of an amino acid mixture meet the 2 hour filtration test. It should be pointed out that since heat is known to decrease the viscosity of fluids and of concentrated solutions thereby favoring increased filtration rates, the data provided are not applicable to the solutions of nutrients which would normally be prepared at ambient or room temperature (i.e. 70.degree. F.). Nutrient solutions commonly required in TPN therapy can vary greatly in concentration (e.g. amino acid mixtures can approach 11.4%, dextrose may vary from 5 to 35% and other preparations may reach as high as 40%). Since the viscosity of solutions, in general, increases with concentration and since flow rate through a filter is inversely proportional to viscosity (i.e. low filtration rates with high viscosity; high filtration rates with low viscosity), the gravity filtration method of preparing sterile nutrient solutions proposed by Beigler et al is too slow, time consuming and unacceptable for the wide variety and range of nutrient requirements needed for TPN therapy. Furthermore, lengthy filtration times associated with gravity filtration of concentrated solutions used in TPN therapy may contribute to the growth and release of pyrogens from bacteria which may be present in the solutions and become trapped within the bacterial filter.
To overcome the major problem of slow filtration rates associated with the gravity filtration of nutrient solutions through a fine bacterial filter (0.20 micron), we have developed an Intravenous Delivery System consisting of two (2) compartments (Part 1: Storage/Mixing Chamber; Part 2: Receptacle/Delivery chamber) joined by an in-line filter unit which includes a coarse 5 micron and fine 0.20 micron bacteria filter. Since it is well known that the passage of solutions of varying concentrations through varying type filters are greatly increased by the application or removal of air pressure, this system also includes a separate air pressurizing device which when applied to the Storage/Mixing chamber containing the appropriate dissolved nutrients or medicinal substances will greatly increase the filtration rate making the sterile filtrate appearing in the Receptacle/Delivery chamber readily available for intravenous use in patients.